Method and system for quadrature error compensation

Abstract

The present invention concerns an MEMS sensor and a method for compensation of a quadrature error on an MEMS sensor, which is intended for detection of movements of a substrate, especially accelerations and/or rotation rates. At least one mass arranged on the substrate and mounted to move relative to it is driven by means of drive electrodes. The mass/es execute a movement deviating from the prescribed movement due to a quadrature error. A deflection of the mass/es occurring due to Coriolis force and quadrature error is detected with detection electrodes. It is proposed according to the invention that a capacitance change be detected as a function of drive movement of the mass/es by means of compensation electrodes. A compensation charge dependent on the quadrature error of the MEMS sensor is generated on the compensation electrodes. For compensation, the distorted or incorrect charge generated by the quadrature error in the detection electrodes is compensated with the compensation charge.

We claim: 
     
       1. A method for compensating a quadrature error on a MEMS sensor, the method comprising:
 detecting a movement of a drive mass within the MEMS sensor, the movement of the drive mass being relative to drive electrodes and having a deviation from a prescribed movement due to a quadrature error; 
 identifying a capacitance change as a function of drive movement of the drive mass using a compensation electrode; 
 generating a compensation charge on the compensation electrode, the compensation charge being dependent on the quadrature error; and 
 compensating the quadrature error using the compensation charge. 
 
     
     
       2. The method of  claim 1  wherein the step of compensating the quadrature error is performed by canceling at least a portion of a quadrature error charge with the compensation charge. 
     
     
       3. The method of  claim 1  wherein a predetermined voltage dependent on the quadrature error is applied to compensation electrodes to generate the compensation charge. 
     
     
       4. The method of  claim 1  wherein the compensation charge and the capacitance change are processed relative to each during a process of compensating quadrature error. 
     
     
       5. The method of  claim 1  wherein the compensation charge and the capacitance charge are provided to evaluation circuitry. 
     
     
       6. The method of  claim 5  wherein the evaluation circuitry identifies a compensation process for compensating the quadrature error. 
     
     
       7. The method of  claim 1  wherein the compensation charge is controlled based on the quadrature error. 
     
     
       8. The method of  claim 1  wherein a voltage associated with the quadrature error is determined during a test operation of a MEMS sensor. 
     
     
       9. The method of  claim 1  wherein the quadrature error is determined during real-time operation of a MEMS sensor. 
     
     
       10. A MEMS sensor for detecting movement, the sensor comprising:
 a substrate; 
 detection circuitry positioned on the substrate, the detection circuitry detects a deflection of a mass caused at least in part to a quadrature error; 
 capacitive sensor circuitry coupled to detect a capacitance change caused by the deflection of the mass; and 
 compensation circuitry coupled to the capacitive sensor circuitry, the compensation circuitry generates a compensation signal that cancels at least a portion of error caused by the quadrature error. 
 
     
     
       11. The MEMS sensor of  claim 10  wherein the detection circuitry comprises at least one detection electrode that detects a deflection of a mass. 
     
     
       12. The MEMS sensor of  claim 11  wherein the deflection of the mass is caused by a Coriolis force and the quadrature error. 
     
     
       13. The MEMS sensor of  claim 10  wherein the compensation circuitry comprises at least one compensation electrode. 
     
     
       14. The MEMS sensor of  claim 13  wherein the at least one compensation electrode records a capacitance change as a function of a drive movement of a mass. 
     
     
       15. The MEMS sensor of  claim 10  wherein the sensor detects rotation relative to at least two axes. 
     
     
       16. The MEMS sensor of  claim 10  wherein the sensor detects acceleration along an axis. 
     
     
       17. The MEMS sensor of  claim 10  further compnsmg evaluation circuitry that identifies a compensation process for compensating the quadrature error. 
     
     
       18. The MEMS sensor of  claim 17  wherein the evaluation circuitry identifies a compensation charge that offsets at least a portion of the quadrature error.